It has long been desired to maximize fuel economy, power and driveability in diesel fuel powered vehicles while enhancing acceleration, reducing emissions, and preventing hesitation. While it is known to enhance gasoline powered engine performance by employing dispersants to keep valves and fuel injectors clean, such gasoline dispersants are not necessarily effective in diesel fuel applications. The reasons for this unpredictability lie in the many differences between how diesel engines and gasoline engines operate and the chemical differences between diesel fuel and gasoline.
Over the years, dispersant compositions for diesel fuel have been developed. Dispersant compositions known in the art for use in diesel fuel include compositions may included polyalkylene succinimides, which are the reaction products of polyalkylene succinic anhydrides and amines. Dispersants are suitable for keeping soot and sludge suspended in a fluid, however these are not particularly effective for cleaning surfaces once deposits have formed on the surfaces. Hence, diesel fuel compositions that include dispersants often still produce undesirable deposits on diesel engine injectors. Deposits on the injectors may lead to poor fuel economy and per power performance of the engines. The deposits may include coking deposits caused by the combustion of the fuel and internal deposits caused by decomposition or deposition of solids on components of fuel injectors.
Accordingly, improved compositions that can prevent deposit injector and nozzle build up, maintaining “as new” cleanliness for the vehicle life are desired. Ideally, the same composition that can clean up dirty fuel injectors restoring performance to the previous “as new” condition would be equally desirable and valuable in the attempt to reduce air borne exhaust emissions.
In accordance with the disclosure, exemplary embodiments provide a diesel fuel, diesel fuel additive package and method for improving the fuel economy of a diesel engine. The fuel additive includes, in one embodiment, a reaction product of (a) a hydrocarbyl substituted dicarboxylic acid or anhydride, and (b) an amine compound or salt thereof of the formula
wherein R is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 15 carbon atoms, and R1 is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 20 carbon atoms. The reaction product is made at a temperature ranging from about 155° to about 200° C. at atmospheric pressure and contains at least one amino triazole group. Component (2) of the additive package is a hydrocarbyl succinimide dispersant. The additive package also includes (3) a C2 to C10 alkyl alcohol; and (4) optionally, a lubricity additive that, when used, may be present in a weight ratio of component (2) to component (4) in the fuel ranging from about 0.5:1 to about 1.5:1. In the additive package, the hydrocarbyl group of component (1) and (2) is derived from a 500 to 1300 number average molecular weight hydrocarbyl group and a weight ratio of component (1) to component (2) in the fuel ranges from about 1:3 to about 1:5.
Another embodiment of the disclosure provides a method for improving fuel economy of a diesel engine. The method includes combusting a fuel composition containing a major amount of fuel and from 20 mg to 1000 mg per Kg of fuel of a fuel additive composition in the engine. The fuel additive composition includes: (1) a reaction product derived from (a) an amine compound or salt thereof of the formula
wherein R is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 15 carbon atoms, and R1 is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 20 carbon atoms and (b) a hydrocarbyl carbonyl compound of the formula
wherein R2 is a hydrocarbyl group having a number average molecular weight ranging from about 500 to about 1300. The reaction product is made at a temperature ranging from about 155° to about 200° C. at atmospheric pressure and the reaction product contains at least one amino triazole group. Another component of the additive composition is (2) a hydrocarbyl succinimide dispersant derived from a hydrocarbyl group having a number average molecular weight ranging from about 500 to less than about 1300 Daltons and a succinic anhydride. The additive also includes (3) a C2 to C10 alkyl alcohol; and (4) a lubricity additive; and (5) optionally, a demulsifier. A weight ratio of component (1) to component (2) in the fuel ranges from about 1:3 to about 1:5 so that the fuel economy of the diesel engine is improved relative to the fuel economy of the same diesel engine in the absence of the fuel additive composition.
A further embodiment of the disclosure provides a method of cleaning fuel injectors of a fuel injected diesel engine. The method includes combusting a fuel composition in the engine that includes a major amount of diesel fuel and from 20 mg to 1000 mg per Kg of fuel of fuel additive composition. The fuel additive composition includes (1) a reaction product derived from (a) an amine compound or salt thereof of the formula
wherein R is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 15 carbon atoms, and R1 is selected from hydrogen and a hydrocarbyl group containing from about 1 to about 20 carbon atoms and (b) a hydrocarbyl carbonyl compound of the formula
wherein R2 is a hydrocarby group having a number average molecular weight ranging from about 700 to about 1000 and greater than about 60 molar % terminal double bonds. The reaction product is made at a temperature ranging from about 155° to about 200° C. at atmospheric pressure and the reaction product contains at least one amino triazole group. The additive composition also includes (2) a hydrocarbyl succinimide dispersant derived from a hydrocarbyl group having a number average molecular weight ranging from about 700 to less than about 1000 Daltons and a succinic anhydride. Other components of the additive composition include (3) a lubricity additive; and (4) a demulsifier. A weight ratio of component (1) to component (2) in the fuel ranges from about 1:3 to about 1:5. Use of the fuel and additive in the diesel engine provides injectors that are cleaner in the engine combusting the fuel containing the additive composition than injectors in an engine combusting the fuel in the absence of the additive.
An advantage of the fuel additive package described herein is that the additive package may not only reduce the amount of deposits forming on direct and/or indirect diesel fuel injectors, but the additive package may also be effective to clean up dirty fuel injectors, increase fuel economy, and provide improved power performance. The deposit reduction on internal and external injector components and the clean up effect of the additive package may be demonstrated in post 2007 model year engine technology.
Another advantage of the fuel and additives package described herein is that the additive package may provide conductivity properties to a fuel that reduce or eliminate the need for expensive high sulfur containing conductivity additives that are used at fuel terminal locations. Fuels containing the additive package described herein may also exhibit lower corrosion potential in storage and terminal locations. Additional embodiments and advantages of the disclosure will be set forth in part in the detailed description which follows, and/or can be learned by practice of the disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.